// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// File provides basic classes and functions for rANS coding.
#ifndef DRACO_CORE_BIT_CODERS_RANS_BIT_DECODER_H_
#define DRACO_CORE_BIT_CODERS_RANS_BIT_DECODER_H_

#include <vector>

#include "draco/draco_features.h"

#include "draco/core/ans.h"
#include "draco/core/decoder_buffer.h"

namespace draco {

// Class for decoding a sequence of bits that were encoded with RAnsBitEncoder.
class RAnsBitDecoder {
  public:
    RAnsBitDecoder();
    ~RAnsBitDecoder();

    // Sets |source_buffer| as the buffer to decode bits from.
    // Returns false when the data is invalid.
    bool StartDecoding(DecoderBuffer *source_buffer);

    // Decode one bit. Returns true if the bit is a 1, otherwise false.
    bool DecodeNextBit();

    // Decode the next |nbits| and return the sequence in |value|. |nbits| must be
    // > 0 and <= 32.
    void DecodeLeastSignificantBits32(int nbits, uint32_t *value);

    void EndDecoding() {}

  private:
    void Clear();

    AnsDecoder ans_decoder_;
    uint8_t prob_zero_;
};

}  // namespace draco

#endif  // DRACO_CORE_BIT_CODERS_RANS_BIT_DECODER_H_
